PROJECT SUMMARY Electronic cigarettes (ECs) are battery-operated devices that heat a liquid to generate an aerosol vapor inhaled by the user. Despite their increasing popularity, especially among younger users, little is known about the human health effects of EC use. In addition to health concerns about nicotine, flavorings and other chemicals in the liquid, new data from our laboratory, and others, raises concern that ECs may expose users to potentially dangerous metals since a heated wire is used to generate the aerosol, and most coils contain nickel and chromium, known inhalation carcinogens. We hypothesize that EC devices themselves release Ni, Cr and other metals into the heated aerosol and that these potential carcinogens may accumulate in lung tissue and blood. We will test our hypothesis in two ways. First, we will analyze the potential metals contribution of individual components within an EC device by selectively radiolabeling each part individually using Neutron Activation Analysis (NAA) and analyzing its contribution to the metals content of the resultant heated aerosol. Second, we will measure metal concentrations in lung tissue and blood utilizing a mouse model of exposure. We further hypothesize, based on our preliminary studies using ICP-MS analysis of urine and saliva from EC users, and direct measurement of EC aerosol, that variations in coil design, power settings and EC device construction can have significant effects on measured concentrations of Ni, Cr, Pb and other metals. Our Specific Aims include: 1) utilizing NAA to transiently radiolabel various disassembled EC hardware components, followed by reassembly and measurement of the radiation energy spectrum of the collected aerosol to identify specific sources of metal contamination; and 2) mouse exposure experiments to measure and analyze time- and dose-response relationships for Ni, Cr and Pb concentrations in lung and blood following a four week exposure to EC aerosol. Findings from this study are likely to provide crucial and heretofore unavailable information to policy makers to enable them to evaluate potential health risks of toxic metal exposures arising from EC use. We hypothesize that health risks vary depending on operating conditions and specific EC device composition.